Upvote:6
There are insurers that offer coverage for medical evacuation and repatriation, and many designed for J visa holders. Here are the results of a Google search on 'J1 medical evacuation and repatriation insurance:'
Envisage International Student Insurance
Before buying separately, you might contact the insurer(s) available through the university. It may have such coverage and be able to add to your policy, and possibly for less than paying for independent coverage.
Disclaimer: I have no affiliation with any insurance providers, I do have a relative in management at Alphabet Inc.